How to read a text file using adobe javascript

Hi,

I have a api application which adds toolbar to a adobe acrobat. i need to disable the toolbar according to expiry date, So i need to fetch the expiry datge from a text file from the specified location.

I am using importTextData() function to get the textdata from text file using adobe javascript. When i call this function i am getting error "ReferenceError: importTextData() is not defined".

I am using Adobe Acrobat 7.0 version.

Can any one tell how to use the importTextData() function.

Regards

Shiva